Often, in manufacturing processes, it is required to machine the rear face of a hole.
Faces requiring machining or deburring located on a front surface of the workpiece may be machined by any suitable tool. However, faces located on the back surface of the workpiece may be more difficult to machine or deburr because of features of the workpiece which do not allow a standard tool to be utilized or it may be inefficient or difficult to position the workpiece to gain access to the back surface. Backspot facing tools, which are inserted through the aperture and are designed to machine a rear face or remove the burr from the back surface are also known in the art.
One such tool is shown in U.S. Pat. No. 4,710,070, entitled “DEVICE IN BACK SPOT FACING TOOLS”, issued Dec. 1, 1987 to Per Alsen et al (“Alsen”). The Alsen tool includes a spindle with a wing arranged in a recess of the spindle. The wing includes a wing edge. The wing is pivotal between an inactive position to an active position. When in the inactive position, the wing is pivoted such that the wing is within the circumference of the spindle. Thus, the spindle and wing may be inserted through an aperture in the workpiece. When the wing is in the active position, at least part of the wing is located outside the circumference of the spindle. The Alsen tool is designed such that rotation of the tool is one direction acts to move the wing towards the active position and rotation of the tool in the opposite direction acts to move the wing towards the inactive position.
However, the design of the Alsen tool presents several problems which may prevent the tool from closing. First, particles removed from the workpiece may become trapped or stuck between the wing and the shaft. Furthermore, the force acting on the wing to close the tool is due solely to rotation of the shaft.
The present invention is aimed at one or more of the problems identified above.